Hey all, stupid question here, Why would people wire the cooling fan to run whenever the ignition is on? Wouldnt that be harmfull to the alternator in the long run? If you are going to monkey with the fan wiring, wouldnt putting a relay on the brake lights be more appropriate? My thinking is that when the car is moving, the fan is not needed, with the brakes on, the car is at a stop light and there is no air movement through the radiator so the fan would be needed

 

The fan comes on when a temperature is met, the fan switch detects this and makes a connection to the relay in the engine bay fusebox to supply power to the fan to turn on. Once the temperature has dropped it shuts off the fan. The sensor does not detect car movement nor airflow passing the radiator.

edit: the reason why people make the fan to come on and stay on when the ignition is turned is because they either want a temp fix, don't know what they are doing, or was told to do it until the issue is resolved. That issue could be, or mostly due to, overheating.

 

Essentially it's someone who's jury-rigged the fan to deal with a cooling issue that is still unresolved. Fan on/off is controlled by a switch linked to engine temp. The P.O. or whatever punter had their paws in your engine bay failed to fix the actual issue. Now it takes longer for your car to reach operating temps, you're burning more fuel than you need to, yes it's a drain on your alternator sorta, yes it's not necessary, yes it's pretty ******* easy to actually fix the issue with a bit of research.

 

As mentioned in most cases it is just a temp. fix for a problem, a fan that comes on as soon as ign.is on will prevent or slow down engine warm up, not a good thing, again unless just a temp. fix.

In most cases a proper fix is just as easy as a temp. fix, so why not do it correctly. 94

 

Cuz we're getting too old to be tinkering with cars?